• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

The complete 6SN7 preamp

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7N7

7N7

Member
Joined 2003
Brett said:
Paul, I find the software to do underlines italics etc awkward, so perhaps HTML or Markup would be easier. It's what I use, and I just type it in as I go.

HTML
{b}all this will be bold{/b}
{i}and this will be italicised{/i}
{u}and this will be underlined{/u}

To directly link to an image from another site
{img src=image URL}

NOTE: I have used {} brackets where in reality you would use <> for HTML, but if I did, it wouldn't show it as examples, but actually bold, underlined etc in the finished post.
You can also use HTML at audioasylum.


Markup:
Similar to HTML, but uses [] for brackets instead of <>. I'll use {} again for examples so they're visible in the finished post. Notice the capitals.
{B}bold{/B}
{I}italicised{/I}
{U}underlined{/U}
{QUOTE}quoted text{/QUOTE}
{IMAGE}image URL here{/IMAGE}
To add a hyperlink into a sentence, eg

Another audio forum is {URL=http://www.audioasylum.com}Audioasylum{/URL}.

The word Audioasylum would show up in the finished post as a hyperlink, blue and underlined.

You can use both HTML and Markup in this forum in the same post, but you can't start a bold (for example) in html and finish it in markup. Start a function in one style, and you must finish it with the same.

You can also "nest" functions, eg in HTML (same idea with Markup too),
{i}813's are the {b}best{/b} tubes{/i}. The entire sentence would be in italics, with the word 'best' bold too.

HTH

Cheers
Click to expand...

Thanks for that.

I did try but it had no effect. Perhaps I should try {U} in future{U}!

7N7
 
Brett

Brett

Member
Joined 2002
7N7 said:


Thanks for that.

I did try but it had no effect. Perhaps I should try {U} in future{U}!

7N7
Click to expand...
No you were correct in using the [] brackets, but you need to "close" each sequence with a [/*] with the appropriate letter in place of the *, or the forum server won't recognise the sequence as markup and just assume it's text with square brackets in it and not perform the desired function.

Cheers
 
7N7

7N7

Member
Joined 2003
Brett said:
No you were correct in using the [] brackets, but you need to "close" each sequence with a [/*] with the appropriate letter in place of the *, or the forum server won't recognise the sequence as markup and just assume it's text with square brackets in it and not perform the desired function.

Cheers
Click to expand...

Brett,

Thanks for your patience

Ha-ha!! It works:cool:

7N7
 
fdegrove

fdegrove

diyAudio Senior Member
Joined 2002
HEATERS.

Hi,

When you connect pins # 4 + # 5 together you put both filaments in //.

If you only use 1 section (say triode # 1) you can then connect to pins # 4 and # 9

Since we have an identical twin triode on the other channel and this one is using triode # 2 you can now hook up to pins # 5 and # 9.

As John suggested before you can now swap the tubes around once they're used.

Cheers,;)
 
B

Burnedfingers

Member
Joined 2002
Frank, Joel, and others

I do appreciate the help. I do have the heaters wired correctly now. I did install the 100ohm pot and go for null.

I have a B+ voltage of around 240volts so I can use my 5692's when the hum is beaten like a sick mule. I do plan to heat the workshop tonight and see what I can come up with on the noise problem and will advise.

Joe
 
Joel

Joel

Member
Joined 2002
joeltunnah.com
Frank, 7N7, and Corbato - PLEASE take your posts on that other amp to a new thread. Otherwise they will get lost in the future, and they have NOTHING to do with this one. Thank you.:mad:

Joe, if it's a quite noticable hum on speakers, then it will be a quite noticable mistake - when you find it!

1) Look over the entire circuit again - look for reversed electrolytics, missing parts, and check all the resistor and cap values.

2) Ground the input tube's grid - does the noise go away, or not?

3) What frequency is the hum?

4) Take readings of all the electrodes' voltages. Anything unusual stand out?

5) what type of jacks (in/out) are you using, and how are they grounded?
 
Joel

Joel

Member
Joined 2002
joeltunnah.com
Joe, 60 cycle hum is not a PS issue, IME. Yes, it could be related to the transformer - but only in some sort of layout sense.
I don't know what type of layout you used, box size, etc.

To give you an idea, I used a 280V transformer, with the circuit I posted, and put the whole thing in a 6"x10"x2" hammond steel box. No hum - even with headphones. This is the layout I used:
 

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Joel

Joel

Member
Joined 2002
joeltunnah.com
burnedfingers said:
Joel
I noticed that you used a 6C8G instead of a 12ay7 in you lineamp.
Is their a reason why you used this tube?
Click to expand...

Hi Joe,

Actually I didn't have any 12AY7's at home at the time, and I was too impatient to wait for them to arrive - so I used a 6C8, which is very close in gain. They are somewhat microphonic though, so I'd leave them for phase inverter duties, like they were designed for. Pretty tube though, ST shape with a top cap.
 
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